Ask Mr. Wizard

A Beer’s Changing Flavor Profile


Shawn Poggemiller — Dubuque, Iowa asks,

I have brewed a Founders Brewing Co.’s Breakfast Stout clone from the BYO Big Book of Clone Recipes every year when it gets cold outside. It is fantastic and find it gets very close to Founders’ version. I brew the recipe exactly as printed using cocoa nibs and Kona and Sumatran coffees. One thing I have noticed is that the Founders’ beer seems to have a very consistent flavor profile with a nice balance of the chocolate and coffee while the chocolate and coffee flavors in my homebrewed version change dramatically over a period of about three months. In the beginning, the coffee flavor is dominant and it can be difficult to taste any chocolate. After a few weeks the coffee calms down and a milk chocolate flavor starts to appear. After a few more weeks the coffee flavor turns really earthy and the chocolate flavor turns dry and almost bitter. Is there a way to stabilize these flavors?


Just reading this question makes me want to stop writing and go find one of these great beers! Describing off-flavors can be difficult, especially in beer styles with a combination of special ingredients like coffee and chocolate, special malts, and alcohol. Whether my hunches are correct about the causes of your specific problems are correct or not, they certainly will not hurt anything when followed.

The first thing that comes to mind is oxidation because oxygen has a way of dulling most fresh flavors in beer, wine, and food. And oxidation has an irritating way of changing the flavor of beer over time, like you are describing in your Founders Breakfast Stout (FBS) clone. When in doubt, consider oxidation! However, obsessing about oxygen can become bothersome and paralyzing at times, but a healthy respect of the negative effects of oxygen on beer flavor stability is a good thing. One of the easiest and most effective practices to ward off oxygen, especially in stronger beers that may spend a longer time in the fermenter, is to rack into a keg. I know the trend these days is one-pot everything, but racking has some real benefits.

A batch of cold-brewed coffee is an easy and impactful way to impart coffee flavor in your brew. Photo courtesy of

Benefit #1 to racking is ditching some yeast. This can certainly be done without racking if your fermenter has a valve on the bottom that allows for purging, but a lot of brewers still ferment in containers without this feature. I’m not sure what you use, but consider racking if you are aging on yeast. What does racking and yeast sediment have to do with beer stability? Well, when yeast is left lying on the bottom of a fermenter, especially beneath higher-alcohol beer, it dies and decays (lyses) over time. And when yeast cells break apart as autolytic enzymes do their thing, these and other enzymes spill into beer. This cocktail of enzymes can lead to enzymatic degradation of beer aroma compounds from esterases, degradation of beer foam from proteolytic enzymes, a general dulling of aroma, and the development of umami flavors (soy, meaty, brothy). Getting yeast sediment away from beer is always a good idea after the heavy lifting of fermentation is over.

Another benefit of racking into a keg is to definitively seal the beer up from the environment. This can also be done in a stainless fermenter, but not all homebrewers have these silver gems. Filling a Corny keg with water, blowing down with carbon dioxide, and racking in through the dip-tube is an easy and effective way of moving beer. Since the Founders clone has coffee grounds added to the fermenter, racking also gets the beer off of the coffee. Sitting on grounds for prolonged durations may lead to issues.

If your beer is bottled, check out your process and make sure you are doing everything you can to minimize oxygen in the package.

If your beer is bottled, check out your process and make sure you are doing everything you can to minimize oxygen in the package. Bottling is a major thing for homebrewers because beer does not foam when filling flat beer into bottles. Many brewers, both commercial and recreational, place way too much faith in the antioxidant property of yeast. Chemical oxidation occurs very rapidly and sleepy yeast are unlikely to absorb oxygen introduced during packaging fast enough to prevent beer oxidation. Founders packages all of their major brands after carbonation and is able to crown/lid on foam. This is a great way of pushing air out of the bottle headspace. If you are capping flat beer, that air in the headspace is 19% oxygen. Adding some fresh yeast at bottling time is one way to address this issue, especially for beers that are being bottled with priming sugar 4+ weeks after brewing. But don’t be tempted to fill bottles with little to no headspace. My preference is to counter-pressure fill and crown on foam, even when doing some secondary fermentation in the bottle. That’s a discussion for another day.

Besides oxidation and prolonged exposure to yeast sediment, another thing that pops to mind is ingredient selection. Although the types of coffee and chocolate are specified in the recipe, no specifics about quality is provided. Quality can be a nebulous term and it’s impossible to have agreed upon quality metrics without some sort of testing methods. Cacao nibs, chocolate, and, especially, roasted coffee all are subject to oxidation. The general advice from coffee roasters about the storage of roasted beans is to use them within about two weeks of roasting for the freshest flavor. Ingredient quality, particularly with non-traditional brewing ingredients, can be a real game changer. Not much more to comment on this without knowing more about your coffee and chocolate sources. The bottom line is that you want fresh ingredients with great taste and aroma profiles.

The last thing that comes to mind is probably a stretch, but water chemistry is certainly an important factor for all beers. Aroma decay is not something associated with water chemistry, but the balance of a beer without a lot of roasted malt and roasted adjuncts can definitely be affected by water.

Years ago, I heard a great story from a practical brewer that was part fable and truth. This brewer proclaimed that the brewery brewed the best, most consistent beer possible, and then the packaging department messed everything up by packaging the brewery’s beer. Not so much a story about throwing the packaging department under the bus, but a story of life and recognizing the finite time we, and our beers, have before succumbing to the steady beat of the metronome. Extending beer freshness is a multibillion-dollar pursuit and there are no silver bullets. Hopefully some of the tips provided here will help you out. In the meantime, drink your beer fresh and brew more when you run out!

Response by Ashton Lewis.